Dewatering method for correcting water content of green veneer for plywood and apparatus for dewatering the green veneer

ABSTRACT

A large number of green veneers for plywood respectively having high water contents and formed in a rectangular shape are vertically laminated to obtain a veneer laminate having a quadrangular prismatic shape. The veneer laminate is located between upper and lower platen members so that two opposite side faces of the veneer laminate vertically form cut face gathering planes. The upper and lower platen members are moved toward each other to apply a pressing force to the veneer laminate. The pressing force applied to the veneer laminate is released or weakened while the water drawn through the cut face gathering planes by the pressing force is dripping downward along the cut face gathering planes of the veneer laminate vertically formed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. utility application entitled,“Dewatering Method for Correcting Water Content of Green Veneer forPlywood and Apparatus for Dewatering the Green Veneer,” having Ser. No.13/539,659, filed Jul. 2, 2012, issuing as U.S. Pat. No. 9,259,890,which is entirely incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a dewatering method for correcting watercontents of green veneers for plywood. In the dewatering method, apressure is vertically applied to a large number of vertically laminatedgreen veneers for plywood so that the green veneers are compressed anddewatered for reduction of water contents of the green veneers. Theinvention also relates to an apparatus for dewatering the green veneers.

Description of the Related Art

Describing a plywood production process often employed, a log beingrotated is peeled into thin band plates by the use of a lathe (plane),green veneers are obtained by cutting the peeled band plates inpredefined dimensions and then dried, and a plurality of the greenveneers is bonded to produce the plywood. In the process, the greenveneers are compressed and dewatered by applying a pressure to the greenveneers before the drying step because it is time-consuming toimmediately dry the obtained green veneers.

The water contents of the respective green veneers thus dewatered aredesirably as equal as possible not only among the laminated greenveneers but also in different parts of each green veneer. A largedifference between the water contents leads to a lengthy drying step andmakes it difficult for the green veneers to be equally dried, in whichcase the water contents are still different from one green veneer toanother and in different parts of one green veneer after the dryingstep. When the green veneers thus having different water contents arelaminated to produce the plywood, warp and/or distortion is likely tooccur.

Comparing sapwood and core pieces respectively obtained from outerlayers and a core part of the log, the water contents of each greenveneer before compressing step are largely different. For example, thewater content of the sapwood is twice to three times as large as arelatively low water content of the wood core. When the sapwood and corepieces, each one of which is inadequate and unusable as a veneer, arejoined and used as a patched veneer, the veneer may have water contentstwo-fold to three-fold different from one another in different parts ofthe patched veneer. In some of such green veneers, there may bedifferences by several-ten percentages or more among the water contentsin different parts of one green veneer. The Applicant was granted twopatents in Japan last year, U.S. Pat. No. 4,783,862 and U.S. Pat. No.4,783,863 (both registered on Jul. 15, 2011). This invention is anindependent invention distinctly different from these two patentedinventions.

-   [Patent Document 1] Japanese Laid-Open Patent Publication No.    2002-166403-   [Patent Document 2] Japanese Laid-Open Patent Publication No.    2010-197004

The Patent Document 1 discloses a roller dewatering apparatus. In theapparatus, green veneers are each transported through between squeezerollers to be thereby pressed and dewatered. This apparatus whichdewaters the green veneers one by one needs an extensive time for itswhole operation. Further, the apparatus, wherein all of the greenveneers are uniformly pressed by the rollers, is unable to correct avariability of water contents among the different green veneers.

The Patent Document 2 discloses a dewatering apparatus configured forlaminate collective compression. In the apparatus, laminated greenveneers are pressed collectively from an upper direction to bedewatered. The apparatus thus dewatering all of the green veneers atonce achieves a better dewatering efficiency. However, the apparatus issimilarly unable to correct a variability of water contents, whetherthey are different water contents among the green veneers and/ordifferent water contents in different parts of one green veneer.

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The invention provides a method and an apparatus for dewatering aplurality of green veneers while reducing a variability of watercontents during the dewatering treatment.

Means for Solving Problems and Operational Effect

The invention provides a dewatering method as described below. A largenumber of green veneers for plywood respectively having high watercontents and formed in a rectangular shape are vertically laminated toobtain a veneer laminate having a quadrangular prismatic shape. Cutfaces of the green veneers for plywood, which are end faces of the greenveneers for plywood intersecting with a direction of fibers, arevertically aligned. The veneer laminate is located between upper andlower platen members so that two opposite side faces of the veneerlaminate vertically form cut face gathering planes. The upper and lowerplaten members are moved toward each other to apply a pressing force inthe range of 15 to 50 kg/cm² (or more preferably in the range of 20 to40 kg/cm²) to the large number of laminated green veneers for plywoodconstituting the veneer laminate. Accordingly, water contained in thegreen veneers for plywood is drawn through the cut faces of the greenveneers and drips downward along the cut face gathering planesvertically formed where the cut faces of the green veneers for plywoodare gathered. The pressing force applied to the veneer laminate isreleased or weakened in the range of 0 to 10 kg/cm² (or more preferablyin the range of 0 to 5 kg/cm²) while the water is dripping downward sothat the cut faces and fibers inside of the green veneers for plywoodspread in a direction of original shape of the green veneers, generatinga negative pressure. The water dripping downward along the cut facegathering planes is suctioned into fibers of the green veneer having arelatively low water content by a suctioning action generated from thecut faces toward the inside by the negative pressure. Then, the pressingforce in the range of 15 to 50 kg/cm² is applied again to the largenumber of green veneers for plywood. As a result of at least one cycleof these steps that ends with the application of pressing force, avariability of the water contents in the veneer laminate is lessenedamong the green veneers for plywood and in different parts of each ofthe green veneers for plywood while an overall water content of theveneer laminate is reduced.

The veneer laminate is thus pressed by the upper and lower platenmembers to be dewatered and the pressing force applied to the veneerlaminate is released or weakened while the water is dripping along thecut faces (perpendicular walls) of the veneer laminate. Therefore, thecompressed veneer laminate swells under its own elasticity, generatingthe negative pressure in the fibers of the green veneers, and thedripping water is suctioned into the fibers by the negative pressure.Then, the water drawn from the green veneer or parts of the green veneerhaving the water content relatively high is transferred to the greenveneer or parts of the green veneer having the water content relativelylow. Thus, the green veneers are dewatered such that the water contentshave a less variability from one green veneer to another and indifferent parts of one green veneer. Therefore, the green veneers can bethereafter dried efficiently with less time. When a plurality of greenveneers is bonded to obtain a sheet of plywood, the plywood obtained asa product is unlikely to warp or distort because the water contents ofthe green veneers used in the plywood are not as different from onegreen veneer to another and/or in different parts of one green veneer.

According to an aspect of the invention, a plurality of cycles of thepressing force application—releasing steps or the pressing forceapplication—weakening steps by the upper and lower platen members to theveneer laminate are repeatedly performed and end with the application ofpressing force while the water drawn by the pressing force is drippingdownward along the cut face gathering planes vertically formed.

According to the method, the water is transferred from the green veneeror parts of the green veneer having the water content relatively high tothe green veneer or parts thereof having the water content relativelylow. Then, the green veneers are compressed again so that the water isdischarged from the fibers of the green veneers. When the waterdischarge, the water suction, and the water discharge again areperformed repeatedly, the green veneers can be dewatered such that thevariability of water contents is more effectively lessened from onegreen veneer to another and/or in different parts of one green veneer.

The invention provides a green veneer dewatering apparatus as describedbelow. A large number of green veneers for plywood are verticallylaminated to obtain a veneer laminate, and the veneer laminate issubject to a pressing force vertically applied to the veneer laminate tobe compressed and dewatered to reduce a water content of the veneerlaminate. The apparatus includes:

a support platen supporting the veneer laminate;

a pressing member provided in an upper part of the support platen andmovable toward and away from the support platen;

a pressing cylinder adapted to drive and push the pressing memberagainst the veneer laminate;

a regulating member provided so as to vertically move relative to thesupport platen, the regulating member being adapted to stand uprightfrom the support platen to be in contact with or closely adjacent toperpendicular walls on at least two opposite sides of the veneerlaminate and thereby regulate movement or extension of the veneerlaminate while the veneer laminate is being pressed by the pressingmember, the regulating member further being adapted to abut the pressingmember moving downward to thereafter move downward integral with thepressing member;

a lifting and lowering device adapted to lift and lower the regulatingmember to and from an upright standing position; and

a control device adapted to control the pressing cylinder which drivesthe pressing member, the control device including:

a dewatering pressing stopper which controls the pressing cylinder sothat the pressing force applied by the pressing member to the veneerlaminate for dewatering is released or weakened in the range of 0 to 10kg/cm² (or more preferably in the range of 0 to 5 kg/cm²) and theapplication of pressing force for dewatering stops while the veneerlaminate is being pressed and dewatered by the pressing member under thepressing force in the range of 15 to 50 kg/cm² (or more preferably inthe range of 20 to 40 kg/cm²); and

a dewatering pressing restarter which controls the pressing cylinder sothat the pressing force applied by the pressing member to the veneerlaminate for dewatering is increased in the range of 15 to 50 kg/cm² (ormore preferably in the range of 20 to 40 kg/cm²) to restart theapplication of pressing force for dewatering, wherein

at least one cycle of the application of pressing force for dewateringand the stop of pressing force for dewatering is performed and ends withthe application of pressing force for dewatering.

According to the apparatus, the regulating member reduces a likelihoodof fracture in end portions of the green veneers that may be caused bythe pressing force applied to the veneer laminate, making it difficultfor the green veneers to be damaged by the dewatering treatment.

According to an aspect of the invention, the control device controllingthe pressing cylinder includes: a first pressing stopper adapted to, ina step for subjecting the veneer laminate to a first pressing performedby the pressing member, release or weaken the pressing force applied bythe pressing member while the water contained in the veneer laminate isbeing discharged from the veneer laminate by controlling the pressingcylinder so that the first pressing stops; and a second pressing starteradapted to restart the application of the pressing force to the veneerlaminate by controlling the pressing cylinder so that a second pressingis performed by the pressing member.

Because the pressing force applied by the pressing member is released orweakened while the water is dripping along the perpendicular walls ofthe veneer laminate during the first pressing, the compressed veneerlaminate starts to swell under its own elasticity, generating a negativepressure in the fibers of the green veneers. Then, the water drippingdownward is suctioned by the negative pressure into the fibers of thegreen veneers, and the water discharged from the green veneer or anyparts of the green veneer having the water content relatively high istransferred to the green veneer or parts of the green veneer having thewater content relatively low. When the veneer laminate is compressed tobe pressed and dewatered again in the second pressing for further waterdischarge, difference in the water contents are further reduced amongthe green veneers and/or in different parts of one green veneer duringthe dewatering treatment.

According to another aspect of the invention, the regulating member ispositioned along the perpendicular walls on two opposite sides of theveneer laminate in a direction intersecting with the direction of fibersso that a stretch of the veneer laminate in the direction intersectingwith the direction of fibers is regulated during the application of thepressing force.

This prevents or reduces a likelihood of any stretch of the end portionsof the green veneers in the direction intersecting with the direction offibers, making it difficult for the end portions to fracture.

According to still another aspect of the invention, the apparatusincludes a pair of the regulating members facing each other along theperpendicular walls on opposite two sides of the veneer laminate, and alateral movement device adapted to move one of the pair of theregulating members toward the other regulating member. The lifting andlowering device locates one of the pair of the regulating members at astandby position below a veneer supporting surface of the support platenwhen ready to place the veneer laminate on the support platen, and thenlifts the one of the pair of the regulating members so as to standupright on the support platen after the veneer laminate is placed on thesupport platen. The lateral movement device moves the one of the pair ofthe regulating members toward the other regulating member so that theveneer laminate is thereby sandwiched from two sides intersecting withthe direction of fibers.

According to the apparatus, neither of the regulating members interfereswith the veneer laminate when placed on the support platen, and theveneer laminate is sandwiched by the regulating members from two sidesbecause one of the regulating members is moved toward the otherregulating member after the veneer laminate is placed on the supportplaten. As a result, any stretch and fracture of the end portions of thegreen veneers are more effectively prevented or less likely while thepressing force is being applied to the green veneers.

In the apparatus according to still another aspect of the invention, aplurality of the pressing cylinders is coupled at different positionswith the pressing member of pressing cylinders to drive the pressingmember, and a plurality of lifting cylinders is coupled at differentpositions with the pressing member. The lifting cylinders are drivenwhen the pressing member is lifted to return to a lift-up position afterthe pressing of the veneer laminate by the pressing member is over. Theapparatus further includes: a stroke distance measuring device adaptedto measure a stroke distance of each of the lifting cylinders thatfollow the plurality of the pressing cylinders while the plurality ofthe pressing cylinders is pressing the veneer laminate by the use of thepressing member; and a per-cylinder control device adapted toindividually control the plurality of the pressing cylinders so as tolessen a deviation between the stroke distances of the lifting cylindersmeasured by the measuring device or a tilt of the pressing membercalculated from the deviation.

According to the apparatus, the lifting cylinders having outputsrelatively small but large enough to lift the pressing member are usedto return the pressing member to the lift-up position, making itunnecessary to drive the pressing cylinders with very large outputs.This leads to energy saving. Further, in the apparatus, the strokedistances of the plurality of lifting cylinders is measured and theplurality of pressing cylinders is individually controlled so that thetilt of the pressing member is corrected based on the measured values.The apparatus can horizontally retain the veneer laminate as equally inheight as possible during the pressing, thereby evenly dewatering theveneer laminate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view conceptually and schematically illustrating anapparatus suitably used in a dewatering method according to theinvention;

FIG. 2 is a front view which corresponds to FIG. 1, illustrating a stepof the dewatering method according to the invention relevant to anoperation of the apparatus;

FIG. 3 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 2;

FIG. 4 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 3;

FIG. 5 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 4;

FIG. 6 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 5;

FIG. 7 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 6;

FIG. 8 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 7;

FIG. 9 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 8;

FIG. 10 is a front view, similarly illustrating an operation and a stepof the method subsequent to the illustration of FIG. 9;

FIG. 11 are plan views, similarly illustrating operations and steps ofthe method which correspond to the illustrations of FIGS. 4 and 5;

FIG. 12 is a plan view drawn to describe an effect of FIG. 11;

FIG. 13 is another plan view drawn to describe the effect of FIG. 11;

FIG. 14 is a schematic plan view drawn to describe the effect of FIG.11;

FIG. 15 is a front view of a veneer laminate B1, illustrating a functionwhich corresponds to the illustration of FIG. 7;

FIG. 16 is a side view of the illustration of FIG. 15.

FIG. 17 is a perspective view of the illustration of FIG. 15;

FIG. 18 is a conceptual view drawn to describe water transfer in theveneer laminate B1;

FIG. 19 is a plan view of a patched veneer;

FIG. 20A is a plan view illustrating water transfer in the patchedveneer of FIG. 19;

FIG. 20B is a front view of the illustration of FIG. 20A;

FIG. 21 are conceptual views illustrating water discharge and suctioningmechanisms in green veneers which correspond to the illustrations ofFIGS. 6 to 8;

FIG. 22A is a graph which confirms an effect accomplished by thedewatering method according to the invention;

FIG. 22B is a table illustrating a relationship among dewateringpressure, release pressure, and water content uniformity;

FIG. 23 is a drawing of an oil pressure system, illustrating anotherapparatus suitably used in the dewatering method according to theinvention;

FIG. 24 is a drawing of a control system in the illustration of FIG. 23;

FIG. 25 is a schematic front view of the apparatus, illustrating anoperation including lifting cylinders;

FIG. 26 is a front view, more specifically illustrating the apparatus ofFIG. 25;

FIG. 27 is a side view of the illustration of FIG. 26;

FIG. 28 is a plan view of a lower part in the illustration of FIG. 26;

FIG. 29 is a schematic illustration of operations of a lateral movementdevice and a regulating member illustrated in FIGS. 26 to 28;

FIG. 30 is a front view which corresponds to FIG. 1, illustrating stillanother apparatus suitably used in the dewatering method according tothe invention;

FIG. 31 is a front view illustrating a step subsequent to theillustration of FIG. 30;

FIG. 32 is a front view illustrating a step subsequent to theillustration of FIG. 31;

FIG. 33 is a schematic front view illustrating a first example of amethod for detecting dripping water;

FIG. 34 is a front view illustrating a second example of the method;

FIG. 35 is a front view illustrating a third example of the method; and

FIG. 36 is a front view illustrating a fourth example of the method.

EXEMPLARY EMBODIMENT FOR CARRYING OUT THE INVENTION

An exemplary embodiment of the invention is described referring toexamples illustrated in the accompanied drawings. First, a dewateringapparatus for correcting water contents suitably used in a methodaccording to the invention is described. Then, examples of the methodaccording to the invention are described in a manner that corresponds tothe description of operations of the apparatuses. FIG. 1 illustrates agreen veneer dewatering apparatus 1 adapted to vertically apply apressing force and thereby compress a veneer laminate (green veneerlaminate) composed of a large number of vertically laminated greenveneers for plywood to dewater the veneer laminate for reduction of awater content of the veneer laminate. The green veneer dewateringapparatus 1 has a support platen 2 supporting the veneer laminate, apress platen 3 provided in an upper section of the support platen 2 andserving as a pressing member movable toward and away from the supportplaten 2, a pressing cylinder 4 adapted to drive the press platen 3 andpush the press platen 3 against the veneer laminate, a pair ofregulating members 5 provided so as to vertically move relative to thesupport platen 2, the regulating members 5 being adapted to standupright from the support platen 2 to be in contact with or closelyadjacent to perpendicular walls on at least two opposite sides of theveneer laminate to thereby regulate movement or stretch of the veneerlaminate while the veneer laminate is being pressed by the press platen3, the regulating members 5 further being adapted to abut the pressplaten 3 moving downward to thereafter move downward integral with thepress platen 3, a lifting and lowering cylinder 6, which is an exampleof the lifting and lowering device, adapted to lift and lower theregulating members 5 to and from the upright standing position, and apressing controller 7, which is an example of the control device,adapted to control the pressing cylinder 4 which drives the press platen3. The support platen 2 and the press platen 3 are examples of the upperand lower platen members.

The support platen 2, the pressing cylinder 4, and the lifting andlowering cylinder 6 are secured to a frame 8. The frame 8 is formed in abox shape, and the support platen 2 is located so as to horizontallytraverse the frame 8. A transport-in conveyer 11 which transports aveneer laminate B1 to the support platen 2 is connected to one side ofthe support platen 2, and a transport-out conveyer 12 which transports aveneer laminate B2 already compressed and dewatered from the supportplaten 2 is connected to the other side of the support platen 2.

The pair of regulating members 5 each has a planar (plate-like) shapefacing perpendicular walls on opposite two sides of the veneer laminateB1 and stand upright in parallel with each other. The green veneers havea square-like shape (conventionally, rectangular shape). When adirection of fibers and a direction intersecting with the direction offibers are identified in the green veneer, the two perpendicular wallson two sides are in parallel with the direction of fibers. Therefore, apair of the regulating members 5 is facing each other in the directionintersecting with the direction of fibers of the green veneers, and endfaces of the fibers of the green veneers are exposed in a directionorthogonal to a plane of paper in the illustration of FIG. 1. These endfaces constitute cut face gathering planes where cut faces of the greenveneers are gathered.

As an example of the lateral movement device, lateral movement cylinders13 and 13 are provided to move one of the pair of regulating members 5toward the other regulating member 5. The lateral movement cylinders 13and 13 are respectively connected to the regulating members 5. Thelateral movement cylinders 13 and 13 are secured to lifting and loweringbases 14, and piston rods 15 of lateral movement cylinders 13 arecoupled with the regulating members 5. The pair of regulating members 5each stands upright to extend upward through moving spaces 16 formed inthe support platen 2. The regulating members 5 are horizontally movablerelative to the lifting and lowering bases 14 while retaining theirupright positions within the moving spaces 16. When at least one of thelateral movement cylinders 15 is driven to laterally move one of theregulating members 5 toward the other regulating member 5, the veneerlaminate B1 is thereby sandwiched from two sides in the directionintersecting with the direction of fibers.

The lifting and lowering bases 14 are coupled with piston rods 17 oflifting and lowering cylinders 6 and 6 vertically installed. Theregulating members 5 are coupled with the lifting and lowering cylinders6 via the lifting and lowering bases 14 which respectively support thelateral movement cylinders 13. The lifting and lowering cylinders 6 eachhas a stroke which lifts and lowers each of the regulating members 5between an upright standing position where an upper end of each of theregulating members 5 protrudes upward through the support platen 2beyond a height dimension of the veneer laminate B1 and a standbyposition below an upper surface of the support platen 2. The lifting andlowering cylinders 6 each has a vertical guide member vertically formed,not illustrated in the drawings, which directly guides each of theregulating members 5 upward and downward or indirectly guides each ofthe regulating members 5 by the use of a fitment formed integral witheach of the regulating members 5. When the regulating member 5 on theside of the transport-in conveyer 11 alone is at the standby positionbelow the upper surface of the support platen 2 in the apparatusillustrated in FIG. 1, the veneer laminate B1 is transported onto thesupport platen 2. When at least the regulating member 5 on the side ofthe transport-out conveyer 12 is at the standby position below the uppersurface of the support platen 2 in the apparatus, the dewatered veneerlaminate B2 is transported from the support platen 2.

The support platen 2 has therein a built-in conveyer 20 adapted to liftitself slightly above the upper surface of the support platen 2. Thebuilt-in conveyer 20 is, for example, a chain conveyer driven beingsupported by sprockets 21 and 22 provided on both end sides of thesupport platen 2. The conveyer 20 is moved by a lifting and loweringdevice 23 (for example, lifting and lowering cylinder) to and from atransport position slightly above the upper surface of the supportplaten 2 and a standby position below the upper surface. The built-inconveyer 20, when driven at the transport position slightly above theupper surface, guides the veneer laminate B1 transported by thetransport-in conveyer 11 to the support platen 2. When the conveyer 20is retreated to the standby position, the veneer laminate B1 is placedon the upper surface of the support platen 2. The dewatered veneerlaminate B2 is slightly lifted when the built-in conveyer 20 is liftedby the lifting and lowering device 23 and transported by the built-inconveyer 20 from the support platen 2 toward the transport-out conveyer12 and thereby received by the transport-out conveyer 12.

The pressing controller 7 which controls the pressing cylinder 4 has afirst pressing stopper adapted to, in a step for subjecting the veneerlaminate B1 to a first pressing performed by the press platen 3, releaseor weaken a pressing force applied by the press platen 3 while the watercontained in the veneer laminate B1 is being discharged from the veneerlaminate B1 by controlling the pressing cylinder 4 so that the firstpressing stops; and a second pressing starter adapted to restart theapplication of the pressing force to the veneer laminate B1 bycontrolling the pressing cylinder 4 so that a second pressing isperformed by the press platen 3. More specifically, the pressingcontroller 7 includes: at least a sequence program 25 run by a CPU tocontrol a pressing pattern of the pressing cylinder; and a timer 26measuring pressing times and pressing-release times. The controller 7 isconnected to a pressure sensor 28 which detects a pressure level of thepressing cylinder 4, an electromagnetic valve 29 which controls a fluidpressure (normally, oil pressure) to the pressing cylinder 29, and, ifnecessary, a pressing force source such as an oil pressure pump 30. Thefirst pressing stopper and the second pressing starter include thesequence program 25 and the timer 26.

Next, operation steps of the green veneer dewatering apparatus 1 asdescribed above are hereinafter described. The description given belowincludes details of the sequence program 25 of the pressing controller 7and an example of the dewatering method for correcting water contentsaccording to the invention.

When the veneer laminate B1 is transported by the transport-in conveyer11 as illustrated in FIG. 1, the regulating member 5 on the side of thetransport-in conveyer 11 is moved downward by the lifting and loweringcylinder 6 to the standby position below the upper surface of thesupport platen 2 as illustrated in FIG. 2, whereas the other regulatingmember 5 on the side of the transport-out conveyer 12 stays uprightbeyond the height dimension of the veneer laminate B1.

Next, the built-in conveyer 20 illustrated in FIG. 1 is driven, and theveneer laminate B1 on the transport-in conveyer 11 is received by thebuilt-in conveyer 20 and then placed on the support platen 2 asillustrated in FIG. 3. At the time, the built-in conveyer 20 is slightlyabove the upper surface of the support platen 2, and the veneer laminateB1 on the built-in conveyer 20 is afloat. Then, the regulating member 5below the support platen 2 is lifted from the support platen 2 by thelifting and lowering cylinder 6 to a position equal to the veneerlaminate B1 in height or is lifted a little beyond the position so as toprotrude as illustrated in FIG. 4.

Then, the regulating member 5 on the side of the transport-in conveyer11 is laterally moved in a small distance by the lateral movementcylinder 13 toward the regulating member 5 on the opposite side asillustrated in FIG. 5. As a result, the veneer laminate B1 is sandwichedby the pair of regulating members 5 from two sides. The perpendicularwall on one side of the veneer laminate B1 in the direction of fibers isbutted to or located in close proximity of an inner surface of theregulating member 5 on the opposite side, while the perpendicular wallon the other side in the direction parallel to fibers is butted to aninner surface of the regulating member 5 laterally moved. After that,the built-in conveyer 20 illustrated in FIG. 1 is moved downward by thelifting and lowering device 23 to a position lower than the supportplaten 2. Then, the veneer laminate B1 is seated on the upper surface ofthe support platen 2.

Then, the pressing cylinder 4 is driven, and the press platen 3 therebymoves downward as illustrated in FIG. 6. During the downward movement,the press platen 3 abuts upper ends of the pair of regulating members 5protruding upward from the upper face of the veneer laminate B1. A drivepressure of the pressing cylinder 4 is larger than pressures (holdingpressures) of the lifting and lowering cylinders 6 of the regulatingmembers 5. After the press platen 3 abuts the upper ends, therefore, thepressing cylinder 4 pushes the pair of regulating members 5 downwardwhile pushing the pistons of the lifting and lowering cylinders 6downward.

As illustrated in FIG. 7, as soon as the press platen 3 is butted to theupper face of the veneer laminate B1 (green veneer at the top) duringthe process, the veneer laminate B1 starts to be compressed by thepressing force applied to the veneer laminate B1. Then, the press platen3 driven by the pressing cylinder 4 continues to apply the pressingforce to the veneer laminate B1 over a predetermined period of time bymoving the pair of regulating members 5 downward.

The veneer laminate B1 is vertically compressed by the pressing forcethus applied to the veneer laminate B1 and thereby relatively reduced inheight, and the water contained in the respective green veneers issqueezed out through the end faces of the green veneers in the directionof fibers (for example, perpendicular wall on the front illustrated inFIG. 7) and drips downward. During the dewatering treatment, the driveof the pressing cylinder 4 is suspended to release the pressing force(make the pressing force zero) to the veneer laminate B1 from the pressplaten 3 or weaken the pressing force to a lower level as illustrated inFIG. 8. This is the stop of the first pressing while the water isdripping.

In a short period of time after the pressing stopped, the pressingcylinder 4 is driven again to proceed to a second pressing where theveneer laminate B1 starts to be pressed again by the press platen 3 asillustrated in FIG. 9.

After the second pressing performed for a predetermined short period oftime, it is suitably selected whether the dewatering treatment to theveneer laminate B1 is ended or a third pressing starts after the secondpressing stopped, while the water squeezed out of the fibers of thegreen veneers during the second pressing was dripping. As illustrated inFIG. 10, the pressing cylinder 4 is driven to the backward directionafter an Nth pressing (N is an integer equal to or larger than 2) isover, and the press platen 3 starts to move upward and moves away fromthe upper face of the dewatered veneer laminate B2 and the upper ends ofthe pair of regulating members 5.

Then, the regulating member 5 at least on the side of the transport-outconveyer 12 is moved downward by the lifting and lowering cylinder 6until the upper end of the regulating member 5 arrives at the standbyposition below the upper surface of the support platen 2. The built-inconveyer 20 illustrated in FIG. 1 is moved upward by the lifting andlowering device 23 so that the dewatered veneer laminate B2 is therebylifted from the support platen 2 and ready to be transported by thebuilt-in conveyer 20. When the conveyer 20 is driven, the veneerlaminate B2 moves away from the support platen 2 and continues to betransported by the transport-out conveyer 12 to a predefined site.

The operation of the pressing cylinder in the N-times pressing so fardescribed is controlled by the sequence program 25 run by the pressingcontroller 7 illustrated in FIG. 1. The timer 26 is a structural elementwhich decides duration time of the respective pressing and therespective pressing-release timing. When the times measured by the timer26 are equal to duration time of the respective pressing times andpressing-release timing preset in the sequence program, the pressingcontroller 7 transmits a signal to the electromagnetic valve 29 and, ifnecessary, the pressing force source 30 to suspend or restart theoperation of the pressing cylinder 4. When the pressure of the pressingcylinder 4 obtained from the pressure sensor 28 and the times measuredby the timer 6 are used as parameters for deciding timings of continuingand releasing the pressing force, the application of the pressing forceis continued or released depending on several conditions described bylogical operation such as AND or OR, etc. when the measured pressingforce and times are equal to preset values or included in preset numeralranges.

As a result of the lateral movement of one of the regulating members 5illustrated in FIGS. 4 and 5, the veneer laminate B1 is sandwiched bythe regulating members 5 from two sides as illustrated in plan views ofFIG. 11. This not only lessens or prevents any tilt or misshaping of theveneer laminate B1 while the pressing force is applied to the veneerlaminate B1 but also lessens or prevents any stretch of the end portionsof the green veneers in the direction intersecting with the direction offibers of the green veneers due to the pressing when the veneer laminateB1 is sandwiched from two sides in the fiber-intersecting direction asillustrated in FIG. 12.

An unlimited stretch of the end portions is likely to cause fractures inthe end portions of the green veneers (veneer laminate B1) in thedirection of fibers as illustrated in FIG. 13. However, the pair ofregulating members 5 can prevent the occurrence of such a stretch andresulting fractures in the end portions, as illustrated in FIG. 14.

FIGS. 15 to 18 and 21 are conceptual views (images) of situations of theveneer laminate B1 after the first pressing starts and stops asillustrated in FIGS. 7 to 8 and the second pressing thereafter starts asillustrated in FIG. 9. When the veneer laminate B1 is compressed by thepressing force in the first pressing as illustrated in FIGS. 15 and 16,the water is squeezed from the fibers of the green veneers and dripsdownward along the perpendicular walls of the veneer laminate B1. FIG.21A conceptually illustrates the veneer laminate before the pressingstarts, and FIG. 21B conceptually illustrates the veneer laminatecurrently being pressed. As illustrated in FIGS. 21A to 21C, when thepressing force is released (or weakened) while the water is dripping,the compressed fibers of the green veneers start to swell trying toregain the original shape, and a negative pressure is thereby generatedin the fibers of the green veneers. Under the influence of the negativepressure thus generated, the water dripping along or staying on the wallsurfaces of the veneer laminate B1 is suctioned into the fibers of thegreen veneers. This suctioning under the negative pressure more markedlyoccurs in the green veneer or any parts of the green veneer relativelycontaining less water than the green veneer or any parts thereofrelatively containing more water.

Accordingly, between the fibers of laminated green veneers b1 and thefibers in different parts of each of the green veneers b1, the watertransfer occurs from the green veneer having a high water content to thegreen veneer having a low water content or from any parts of one greenveneer having a high water content to the other parts of the greenveneer having a low water content. In other words, a negative pressurepumping action exerted by the green veneers per se when the pressingforce is released during the dewatering of the green veneers serves toequalize the water contents in the whole structure of the veneerlaminate B1.

Generally, there may be a relatively small variability of the watercontents in one green veneer. To make use of a plurality of differentpieces of wood, each one of which is inadequate and unusable as a veneer(inferior pieces of a log with holes or ruptures, or fragments of thepieces generated when the log with cavities, knots, or uneven peripheryis cut), they may be joined by means of, for example, a tape, so that apatched veneer is formed and used as a material of plywood similarly toone-piece green veneers normally obtained. In a patched veneer b11illustrated in FIG. 19, for example, a sapwood piece A (from outerlayer) of a cedar tree, a heartwood piece B (from mid layer), a sapwoodpiece C, and a core piece D (from center) are patched together. Thereare differences in the water contents of these pieces; twice to threetimes as different between the sapwood pieces A and C having high watercontents and the core piece D having a low water content, and the watercontent of the heartwood piece B is somewhere between the water contentsof these pieces. The negative pressure pumping action, which repeatedlyapplies the pressing force, release the pressing force, and applies thepressing force again, can more effectively transfer the waterparticularly between parts of the patched veneer b11 having moredifferent water contents, thereby equalizing the water contents in thepatched veneer b11, as illustrated in FIGS. 20A and 20B. This is not atechnical advantage limited to the patched veneer. In different parts ofa green veneer obtained from a cedar tree, for example, the watercontent of a part may be larger or smaller by 20% to 150% than theother. Such a large variability is successfully lessened.

The water content equalizing effect thus far described is more enhancedas the release of the pressing force is repeated more often while thegreen veneers are being pressed and dewatered. Therefore, the pumpingaction (negative pressure suctioning) is desirably performed a pluralityof times such that first pressing, release of first pressing while thewater is dripping, second pressing, release of second pressing while thewater is dripping, third pressing, release of third pressing while thewater is dripping . . . .

To improve a dewatering efficiency by reducing a length of time of thedewatering treatment, it is necessary to coordinate how many times thepressing and pressing release should be repeated and a length of time ofthe dewatering necessary for one veneer laminate B1. A suggestion forreducing the dewatering time to the minimum is to complete thedewatering treatment for one veneer laminate B1 in three steps; firstpressing, release of first pressing, and second pressing.

FIG. 22A is a graph illustrating an effect of the dewatering treatmentin the veneer laminate B1 described so far (particularly, effect ofequalizing post-dewatering water contents). In a dewatering testperformed according to the method described so far, water contents ofthe sapwood pieces were about 100% to 300% at most with such a largedifference of 203% in an initial stage (before the dewateringtreatment). However, the variability of the water contents was reducedto 95% after the dewatering treatment according to the invention. Thevariability was further reduced to 5% after the drying treatmentsubsequent to the dewatering treatment.

The cedar core showed the water contents of about 50% to 150% at mostwith the water content difference of 99% in the initial stage (beforethe dewatering treatment). The water content difference was reduced to70% after the dewatering treatment and further reduced to 7% after thedrying treatment.

As illustrated in an upper part of FIG. 22B, 1) illustrates the watercontent uniformity when a cycle of pressing→release→pressing wasrepeated three to five times. The water content uniformity was checkedin combinations of the dewatering pressures of 10, 15, 20, 30, 40, 50,and 60 kg/cm² and the release pressures of 0, 5 and 10 kg/cm². A resultthereby obtained was; the water content uniformity was not very good atthe dewatering pressure of 10 kg/cm² (for example, water contentvariability of around 20% after drying), the water content uniformitywas good at the dewatering pressure of 15 kg/cm² (for example, watercontent variability of at most 15%), the water content uniformity wasgood or very good at the dewatering pressure of 20 to 50 kg/cm² (forexample, water content variability of less than 10%), and the watercontent uniformity was better at the release pressure of 0 or 5 kg/cm²than 10 kg/cm². At the dewatering pressure of 60 kg/cm², the watercontent uniformity was good after drying, however, fractures weregenerated in a part of the green veneers.

As illustrated in a lower part of FIG. 22B, 2) illustrates the watercontent uniformity when a cycle of pressing→release→pressing wasperformed once or repeated twice. The water content uniformity was goodafter drying except for the dewatering pressure of 10 kg/cm², however,the water content variability was smaller when the cycle was repeated atleast three times.

Next, another example of the invention is described referring to anapparatus illustrated in FIGS. 23 to 29.

As is clear from an oil pressure system illustrated in FIG. 23, theapparatus used in the example includes a plurality of (four in thisexample) pressing cylinders 50 which pressurize the veneer laminate B1from an upper direction. The pressing cylinders 50 are coupled with apress platen 51 which is an example of the pressing member, and thepressing cylinders 50 are connected to an oil pressure source 53(compressor or oil pressure pump) through electromagnetic valves 52 ofthe pressing cylinders 50. A plurality of (for example, two each on twosides of the press platen 51, four in total) lifting cylinders 54 iscoupled with the press platen 51 in parallel with the pressing cylinders50 to be located on outer sides of the pressing cylinders 50. Thelifting cylinders 54 are all connected to the oil pressure source 53through a common electromagnetic valve 55. As illustrated in FIG. 24,each of the electromagnetic valves 55 of the plurality of pressingcylinders 50 is connected to a controller (oil pressure controller) 57,and the electromagnetic valve 55 of the plurality of lifting cylinders54 is also connected to the controller 57.

As illustrated in FIG. 25, the lifting cylinders 54 each has a linearencoder 58 incorporated in the lifting cylinders 54 or attached to thelifting cylinders 54 as a measuring device which measures a stroke(operation) distance (stretch distance of piston rods 54 a). Theencoders 58 are connected to the controller 57. When the pressingcylinders 50 are stretched to press the veneer laminate B1 by the use ofthe press platen 51, the piston rods 54 a of the four lifting cylinders54 are stretched as the press platen 51 is moving downward. During thestretch, the linear encoders 58 measure stroke distances (stretchdistances of the piston rods 54 a) L1, L2, L3, and L4 of the liftingcylinders 54 and outputs measured values of the distances to thecontroller 57.

Depending on a difference between the output values of the encoders 58(deviation ΔL) or a three-dimensional tilt Δθ of the press platen 51calculated from the output value deviation ΔL, the controller 57controls the electromagnetic valves 52 of the pressing cylinders 50(FIGS. 23 and 24) so that the deviation ΔL or the tilt Δθ are reduced tothe minimum. Further, the controller 57 separately controls workingpressures P1 to P4 of the pressing cylinders. As a result, the tilt ofthe press platen 51 relative to the veneer laminate B1 is corrected. Thepiston rods 54 a of the lifting cylinders 54 illustrated in FIG. 25,therefore, are coupled rotatably (through a small degree) relative tothe press platen 51. The piston rods 50 a of the pressing cylinders 50may be configured to abut the press platen 51 by means of, for example,hooks not illustrated in the drawings.

When the press platen 51 is lifted to a lift-up position after theveneer laminate B1 is pressed and dewatered by the pressing cylinders50, the pressing cylinders 50 are not driven but the lifting cylinders54 alone are driven (a fluid pressure is supplied from the pressuresource 53 through the electromagnetic valve 55) to elevate the pressplaten 51 to the lift-up position (original position). At the time, thepiston rods 50 a of the plurality of pressing cylinders 50 shrinkfollowing the actions of the lifting cylinders 54. A force for simplylifting the press platen 51 is obtained from the application of acylinder pressure large enough to overcome the weight of the pressplaten 51. If such a cylinder pressure is applied by the pressingcylinders 50 with large outputs, a very large pressure is needed todrive the heavy pistons. However, as far as the small-sized liftingcylinders 54 with low outputs are used to apply such a cylinderpressure, the press platen 51 can be lifted and returned to the originalposition by a small cylinder pressure and a low energy.

The lifting cylinders 54 are stretched in response to the actions of thepressing cylinders 50 (downward movement of the press platen 51), andthe strokes are plotted by the encoders 58. Then, the pressing cylinders50 are separately controlled based on the deviation ΔL or the tilt Δθused as a parameter. Accordingly, the lifting cylinders 54 may be usedwithout additionally providing a specific mechanism to correct the tiltof the press platen 51 during the application of the pressing force.Further, the veneer laminate B1 can be equalized in height and therebyevenly dewatered.

FIGS. 26 and 27 specifically illustrate a positional relationshipbetween the pressing cylinders 50 and the lifting cylinders 54. Thepressing cylinders 50 are secured to inside of a frame 60 which is asecuring member of the apparatus, and the lifting cylinders 54 issecured to an outer side of the frame 60. Referring to FIG. 27, thepiston rods 54 a of the lifting cylinders 54 are coupled with the pressplaten 51 by pins 54 b (for example, rotatable two-dimensionally orthree-dimensionally on at least one of shafts X and Y).

As illustrated in FIG. 26, an upper surface of a support platen 61 isused as a support surface 61 a supporting the veneer laminate B1 placedon the upper surface of a support platen 61. A chain conveyer (built-inconveyer) 62 is provided in parallel with the support surface 61 a. Theconveyer 62 has endless raceways 63 in two rows provided such that theyare hidden immediately below the support surface 61 a (for example,chains), cyclic sprockets 64 and 65 which support the chains 63 so thatthese chains cyclically go around, a plurality of support sprockets 66subject to loads acting on the chains 63, a conveyer frame 67 whichsupports the sprockets 64 to 66, a motor 68 supported by the frame 67which drives the chains 63, and a conveyer lifting and lowering cylinder69 which lifts and lowers the whole structural elements by the use ofthe frame 67.

As illustrated in FIG. 28, the upper surface of the support platen 61(support surface 61 a) has chain grooves (slits) 70 for the chains 63 totravel through. The chains 63 in two rows are lifted and lowered in thechain grooves 70 by the conveyer lifting and lowering cylinder 69 to andfrom a transport position slightly higher than the upper surface of thesupport platen 61 and a standby position lower than the upper surface.While the veneer laminate B1 is being pressurized, the chains 63 are atthe standby position. When the veneer laminate B1 is transported to andfrom the support platen 61, the chains 63 are lifted by the conveyerlifting and lowering cylinder 69 to the transport position. A driveshaft (sprocket) 71 illustrated in FIG. 26 is provided to make thechains 63 in two rows go around in synchronization with each other. Therotation of the motor 68 is transmitted to the sprockets 65 and 71through a driving mechanism such as a chain, and the chains 63 arethereby synchronously driven.

In the illustration of FIG. 26, regulating members 72 which regulatepositions of two opposite sides (two faces) of the veneer laminate B1are supported relative to lateral movement members 73 standing uprightso that the regulating members 72 can be vertically lifted and loweredby the use of lifting and lowering guides 74 as schematicallyillustrated in FIG. 29. Lifting and lowering cylinders 75 which lift theregulating members 72 are secured to the lateral movement members 73,and piston rods 75 a of the lifting and lowering cylinders 75 arecoupled with the regulating members 72. The lateral movement members 73are supported in the frame 60 of the apparatus by the lateral movementcylinders (lateral movement devices) 76. When the lateral movementcylinders 76 are put in action, the regulating members 72, the lateralmovement devices 73, and the lifting and lowering cylinders 75 are alllaterally (horizontally) move at once in a given range of distances.

When the lifting and lowering cylinders 75 are operating (stretching),the regulating members 72 move upward under the guidance by the liftingand lowering guides 74 of the lateral movement members 73. Asillustrated in FIG. 26, the two regulating members 72 facing each otherregulate the positions of opposite two end faces of the veneer laminateB1. As illustrated in FIG. 29, the regulating members 72 are movedhorizontally by the lateral movement cylinders 76 by the use of lateralmovement members 73, and the veneer laminate B1 staying afloat which issupported by the chain conveyer 62 is sandwiched by the regulatingmembers 72.

FIG. 28 is a plan view specifically illustrating the structureschematically illustrated in FIG. 29. On right and left sides of thedrawing are illustrated the structural elements at vertically differentpositions, however, the apparatus in practical use is basicallylaterally symmetrical. The chains 63 of the chain conveyer 62 arelocated in the tracks of the regulating members 72 moving upward anddownward. Therefore, the regulating members 72 are respectively providedwith relief grooves (slits) 77 to avoid any interference with the chains63. The relief grooves 77 are vertically formed in an enough length tomeet the strokes of the regulating members 72 moving upward anddownward. The lateral movement cylinders 76 are secured to the frame 60at positions in front and back of a depth direction of the support plate61 so as to extrude the lateral movement cylinders 76 from the frame 60of the apparatus to the outside at the side of the apparatus, and thelateral movement members 73 standing upright are coupled with thecylinders 76.

The regulating members 72 are located on inner sides of the lateralmovement members 73, in other words, respectively between the lateralmovement members 73 and the frame 60. The regulating members 72 aresupported by the lateral movement members 73 by the use of the liftingand lowering guides 74 so as to move upward and downward and moved toright and left in the illustration of FIG. 28 by the lateral movementcylinders 76. Though not illustrated in FIG. 28, the lateral movementcylinder 76 is provided on the left of the drawing similarly to thelateral movement cylinder 76 on the right, and functions similarlythereto. On the left of the drawing is illustrated a lateral movementguide 78, which functions as a linear guide which couples the lateralmovement member 73 with the frame 60 at a position different in heightto the lateral movement cylinder 76 at positions in front and back of adepth direction of the support plate 61 to guide the lateral movementmember 73 to right and left in the drawing. Though not illustrated inFIG. 28, a lateral movement linear guide is similarly provided on theright of the drawing to guide the lateral movement member 73 on theright to horizontally move.

As illustrated in FIG. 27, the regulating members 72 have longitudinalframe portions 79 and 80 which are rectangular pipe materials eachformed in a frame shape, lateral frame portions 81 and 82 whichvertically connect the longitudinal frame portions, inner spaces of theframe portions 79 to 82, and plate members 83 which seal the spaces. Therelief grooves (slits) 77 in the up-down direction are respectivelyformed in the longitudinal frame portions 79 and 80 so as to fit thechains 63 in two rows. The piston rods 75 a of the lifting and loweringcylinders 75 secured to the lateral movement members 73 are coupled witha lower surface of the lateral frame portion 81 on the upper side.

As illustrated in FIG. 27, the up and down movement of the press platen51 is guided by the lifting and lowering guide 74 formed in the frame60. A pair of upper stoppers 51 a (stopper portions) are formed on alower surface of the press platen 51 with an interval therebetween equalto the outer-side intervals of the pair of regulating members 72 (forexample, long enough to meet a width dimension of the regulating member72 as illustrated in FIG. 27). When the press platen 51 moving downwardmake contact with the upper ends of the pair of regulating members 72,the pair of upper stoppers 51 a are in close proximity of the outersurfaces of the regulating members 72, thereby preventing the pair ofregulating members 72 from opening outward during the application of thepressing force.

Describing the basic operation in the example described so far,similarly to the example illustrated referring to FIGS. 1 to 21, afterthe veneer laminate B1 is transported onto the support platen 61 by thechain conveyer 62 driven by the motor 68 while the regulating member 72on the left in FIG. 26 protrudes from the support platen 61 and theregulating member 72 on the right is receded from the support platen 61,the regulating member 72 on the right in FIG. 26 then protrudes from thesupport platen 61. When the regulating member 72 thus protruding islaterally moved by the lateral movement cylinder 76 toward theregulating member 72 on the left, the veneer laminate B1 is sandwichedby these regulating members 72, and the conveyer lifting and loweringcylinder 69 moves the chain conveyer 62 downward. Then, the veneerlaminate B1 is placed on the upper surface (support surface) 61 a of thesupport platen 61.

Then, the pressing cylinders 50 are driven, and the press platen 51accordingly moves downward and abuts the upper ends of the pair ofregulating members 72. Then, the press platen 51 driven by the pressingcylinders 50 compresses the veneer laminate B1 by pushing the regulatingmembers 72 downward to squeeze the water contained in the veneerlaminate B1. During the process, the stroke distances L1 to L4 of theplurality of lifting cylinders 54 that follow the pressing cylinders areplotted, and the plurality of pressing cylinders 50 is separatelycontrolled so that the press platen 51 is not tilted, in other word, theveneer laminate B1 is horizontally retained equally in height.

When the pressing force applied by the pressing cylinders 50 is releasedor weakened, the compressed fibers of the green veneers start to swell,and a negative pressure is thereby generated in the fibers of the greenveneers. Under the influence of the negative pressure thus generated,the water dripping along the perpendicular walls of the veneer laminateB1 is suctioned into the green veneer or any parts of the green veneerrelatively containing less water. As a result, the water contents aremore efficiently equalized in the green veneers and the whole structureof the veneer laminate B1. Further, the regulating members 72 regulateany stretch of the end portions of the green veneers in the directionintersecting with the direction of fibers, thereby reducing a likelihoodof any fractures in the end portions.

When the dewatering treatment for equalizing the water contents iscompleted after the pressing and the pressing release (or the pressingforce is reduced) are performed by the pressing cylinder 50 a suitablenumber of times (for example, once to three times), the regulatingmembers 72 illustrated in FIG. 26 are both moved downward to a lift-downposition by the lifting and lowing cylinders 75. Then, the chainconveyer 62 is elevated by the conveyer lifting and lowering cylinder 69to lift the dewatered veneer laminate B2 from the support surface 61 aof the support platen 61. The chain conveyer 62 driven by the motor 68transports the veneer laminate B2 from the support platen 61. Then, thesame steps are performed for the next veneer laminate B1.

The example described so far succeeded in reducing the variability ofthe water contents as illustrated in FIG. 22.

The apparatuses illustrated in FIGS. 1, 25, and 26 respectively have theregulating members 5 and 72, the lifting and lowering cylinders 6 and 75which move the regulating members 5 and 72 upward and downward, thelateral movement cylinders 13 and 76 which laterally move the regulatingmembers 5 and 72, and the lifting cylinders 54. According to thedewatering method in which the apparatuses are used, the veneer laminateB1 sandwiched by the regulating members 5 and 72 is pressed from upward.As illustrated in FIG. 30, the method according to the invention may beperformed by a dewatering apparatus 1′ having such a simple structurethat the support platen 2 and the press platen 3 are principalstructural elements. The dewatering apparatus 1′ does not include theregulating members 5 and 72, the lifting and lowering cylinders 6 and 75which move the regulating members 5 and 72 upward and downward, thelateral movement cylinders 13 and 76 which laterally move the regulatingmembers 5 and 72, and the lifting cylinders 54 (other structuralcharacteristics are similar to the illustrations of FIGS. 1, 25, and26).

When the apparatus 1′ is used, the veneer laminate B1 placed on thesupport platen 2 is pressed by the press platen 3 moved downward by thepressing cylinder 4. The pressing force applied by the pressing cylinder4 is released or weakened while the water contained in the veneerlaminate B1 thus pressed is squeezed through the cut faces of the veneerlaminate B1 and dripping downward. A negative pressure is accordinglygenerated in the cut faces of the veneer laminate B1, and the waterdripping downward is suctioned into the fibers. Then, the pressing forceis preferably applied again (second pressing) as illustrated in FIG. 32,and the veneer laminate B1 is dewatered so that the water contents inthe veneer laminate B1 are less variable. After the dewatering treatmentis over, the press platen 3 returns to the lift-up position, and thedewatered veneer laminate B2 is discharged. Then, the same steps areperformed for the next veneer laminate B1.

In the example described thus far, the veneer laminate B1 is pressed tobe dewatered, and the pressing force applied by the press platen 3 isreleased or weakened while the water is dripping downward. The timer 26illustrated in FIGS. 1 and 30 may be used to determine based on testvalues previously obtained that the water is still dripping within atime t1 after the pressing started, and the drive pressure of thepressing cylinder 4 may be released or weakened in response to a time-upsignal of the time t1 as a trigger. However, a different member may beused in place of the timer 26 as described below.

As illustrated in FIG. 33, image pickup cameras 80, for example, may beinstalled in place of the timer near the cut face gathering planes(perpendicular walls) of the veneer laminate B1. Image data of thecameras 80 is transmitted to the controller 7 (pressing controller), andthe pressing controller 7 determines that the water pressed out of theveneer laminate is dripping downward when data indicating the drippingwater, in other words, image (moving image) data including downwarddisplacement is extracted from the image data, and the pressingcontroller 7 outputs a signal for releasing or weakening the drivepressure of the pressing cylinder 4 to the pressing cylinder 4 (to beprecise, electromagnetic valve) while the water is still dripping. Thewater dripping on the side faces of the veneer laminate B1 travelsthrough a water passage 91 formed in the support platen 2 to becollected by a tub 92 and then discharged from the tub 92.

As illustrated in FIG. 34, reflection sensors 83, such as opticalsensors, may be provided so as to face the cut face gathering planes ofthe veneer laminate B1. Reflection signals, which are output from thereflection sensors 83 in response to water screens, water drops, orwater stream while the water is dripping and reflected by the waterscreens on the cut face gathering planes and returned, are transmittedto the pressing controller 7, and the pressing controller 7 determinesthat the water is dripping on the cut face gathering planes of theveneer laminate B1 as far as levels of the reflection signals are equalto or larger than a predetermined threshold value and outputs a signalfor releasing or weakening the drive pressure of the pressing cylinder 4to the electromagnetic valve of the pressing cylinder 4.

As illustrated in FIG. 35, at least sound sensors 84 and/or temperaturesensors 85 may be provided near the cut face gathering planes(perpendicular walls) of the veneer laminate B1. During the water isdropping, output levels of the sound sensors 84 which picked up thesound of the dripping water are equal to a certain value or higher, thetemperature sensors 85 output values within a temperature variation or apredetermined temperature range because of the water dripping, and thepressing controller 7 checks at least one of the output signals of thesound sensors 84 and/or the temperature sensors 85 to release or weakenthe drive pressure of the pressing cylinder 4.

As illustrated in FIG. 36, a container 86 may be provided to receive thewater dripping along the cut face gathering planes of the veneerlaminate B1 through the water passage 91 of the support platen 2. Aweight sensor 87 measures a weight increase of the container 86 wherethe dripping water is stored. As long as the water is dripping, theweight of the container 86 where the water is stored keeps increasing.Therefore, the pressing controller 7, to which a signal from the weightsensor 87 is transmitted, determines whether an amount of the waterstored in the container 86 increases based on the signal output from theweight sensor 87. The pressing controller 7, which detected anyincrease, outputs a signal for releasing or weakening the drive pressureof the pressing cylinder 4 during the increase to induce the compressedveneer laminate B1 to regain the original shape (swell), so that thewater is suctioned into the fibers of the green veneers by a negativepressure suctioning action caused by the swell.

In the illustrations of FIGS. 33 to 36, detecting devices (80 to 87)which detect the water dripping are provided respectively on the cutface gathering planes of the veneer laminate B1 opposite to each otherin parallel. However, these detecting devices (80 to 87) may be providedon one of the cut face gathering planes alone.

What is claimed is:
 1. An apparatus for dewatering green veneers forplywood, wherein a large number of green veneers for plywood arevertically laminated to obtain a veneer laminate, and the veneerlaminate is subject to a pressing force vertically applied to the veneerlaminate to be compressed and dewatered to reduce a water content of theveneer laminate, the apparatus including: a support platen supportingthe veneer laminate; a pressing member provided above the support platenand movable toward and away from the support platen; a pressing cylinderadapted to drive the pressing member and push the pressing memberagainst the veneer laminate; a regulating member provided so as tovertically move relative to the support platen, the regulating memberbeing adapted to stand upright from the support platen to be in contactwith or closely adjacent to perpendicular walls on at least two oppositesides of the veneer laminate to regulate movement or stretch of theveneer laminate while the veneer laminate is being pressed by thepressing member, the regulating member further being adapted to abut thepressing member moving downward to move downward integral with thepressing member; a lifting and lowering device adapted to lift and lowerthe regulating member to and from an upright standing position; and acontrol device adapted to control the pressing cylinder which drives thepressing member, the control device including: a dewatering pressingstopper which controls the pressing cylinder so that the pressing forceapplied by the pressing member to the veneer laminate for dewatering isreleased or weakened in the range of 0 to 10 kg/cm² and the applicationof pressing force for dewatering stops while the veneer laminate isbeing pressed and dewatered by the pressing member under the pressingforce in the range of 15 to 50 kg/cm²; and a dewatering pressingrestarter which controls the pressing cylinder so that the pressingforce applied by the pressing member to the veneer laminate fordewatering is increased in the range of 15 to 50 kg/cm² to restart theapplication of pressing force for dewatering, wherein at least one cycleof the application of pressing force for dewatering and the stop ofpressing force for dewatering is performed and ends with the applicationof pressing force for dewatering.
 2. The apparatus for dewatering greenveneers for plywood as claimed in claim 1, wherein the regulating memberis positioned along the perpendicular walls on two opposite sides of theveneer laminate in a direction intersecting with the direction of fibersto regulate a stretch of the veneer laminate in the directionintersecting with the direction of fibers during the application of thepressing force.
 3. The apparatus for dewatering green veneers forplywood as claimed in claim 1, further comprising: a pair of theregulating members facing each other along the perpendicular walls onopposite two sides of the veneer laminate; and a lateral movement deviceadapted to move one of the pair of the regulating members toward theother regulating member, wherein the lifting and lowering device locatesone of the pair of the regulating members at a standby position below aveneer supporting surface of the support platen when ready to place theveneer laminate on the support platen, and then lifts the one of thepair of the regulating members so as to stand upright on the supportplaten after the veneer laminate is placed on the support platen, andthe lateral movement device moves the one of the pair of the regulatingmembers toward the other regulating member to sandwich the veneerlaminate from two sides intersecting with the direction of fibers. 4.The apparatus for dewatering green veneers for plywood as claimed inclaim 1, wherein a plurality of the pressing cylinders is coupled atdifferent positions with the pressing member to drive the pressingmember, and a plurality of lifting cylinders is coupled at differentpositions with the pressing member, and the lifting cylinders are drivenwhen the pressing member is lifted to return to a lift-up position afterthe pressing of the veneer laminate by the pressing member is over, theapparatus further comprising: a stroke distance measuring device adaptedto measure a stroke distance of each of the lifting cylinders thatfollow the plurality of the pressing cylinders while the plurality ofthe pressing cylinders is pressing the veneer laminate by the use of thepressing member; and a per-cylinder control device adapted toindividually control the plurality of the pressing cylinders so as tolessen a deviation between the stroke distances of the lifting cylindersmeasured by the measuring device or a tilt of the pressing membercalculated from the deviation.